res_send.c

DHCP服务器源码

/*
 * Copyright (c) 1985, 1989, 1993
 *    The Regents of the University of California.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the University of
 * 	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 * 
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/*
 * Portions Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Portions Copyright (c) 1996-2003 by Internet Software Consortium
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *   Internet Systems Consortium, Inc.
 *   950 Charter Street
 *   Redwood City, CA 94063
 *   <[e-mail]>
 *   http://www.isc.org/
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char sccsid[] = "@(#)res_send.c	8.1 (Berkeley) 6/4/93";
static const char rcsid[] = "$Id: res_send.c,v 1.7.2.2 2004/06/10 17:59:44 dhankins Exp $";
#endif /* LIBC_SCCS and not lint */

/* Rename the I/O functions in case we're tracing. */
#define send		trace_mr_send
#define recvfrom	trace_mr_recvfrom
#define	read		trace_mr_read
#define connect		trace_mr_connect
#define socket		trace_mr_socket
#define bind		trace_mr_bind
#define close		trace_mr_close
#define select		trace_mr_select
#define time		trace_mr_time

/*
 * Send query to name server and wait for reply.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/uio.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <errno.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "minires/minires.h"
#include "arpa/nameser.h"

#define	CHECK_SRVR_ADDR
		
static int cmpsock(struct sockaddr_in *a1, struct sockaddr_in *a2);
void res_pquery(const res_state, const u_char *, int, FILE *);

/* int
 * res_isourserver(ina)
 *	looks up "ina" in _res.ns_addr_list[]
 * returns:
 *	0  : not found
 *	>0 : found
 * author:
 *	paul vixie, 29may94
 */
int
res_ourserver_p(const res_state statp, const struct sockaddr_in *inp) {
	struct sockaddr_in ina;
	int ns;

	ina = *inp;
	for (ns = 0;  ns < statp->nscount;  ns++) {
		const struct sockaddr_in *srv = &statp->nsaddr_list[ns];

		if (srv->sin_family == ina.sin_family &&
		    srv->sin_port == ina.sin_port &&
		    (srv->sin_addr.s_addr == INADDR_ANY ||
		     srv->sin_addr.s_addr == ina.sin_addr.s_addr))
			return (1);
	}
	return (0);
}

/* int
 * res_nameinquery(name, type, class, buf, eom)
 *	look for (name,type,class) in the query section of packet (buf,eom)
 * requires:
 *	buf + HFIXEDSZ <= eom
 * returns:
 *	-1 : format error
 *	0  : not found
 *	>0 : found
 * author:
 *	paul vixie, 29may94
 */
int
res_nameinquery(const char *name, int type, int class,
		const u_char *buf, const u_char *eom)
{
	const u_char *cp = buf + HFIXEDSZ;
	int qdcount = ntohs(((const HEADER *)buf)->qdcount);

	while (qdcount-- > 0) {
		char tname[MAXDNAME+1];
		int n, ttype, tclass;

		n = dn_expand(buf, eom, cp, tname, sizeof tname);
		if (n < 0)
			return (-1);
		cp += n;
		if (cp + 2 * INT16SZ > eom)
			return (-1);
		ttype = getUShort(cp); cp += INT16SZ;
		tclass = getUShort(cp); cp += INT16SZ;
		if (ttype == type && tclass == class &&
		    ns_samename(tname, name) == 1)
			return (1);
	}
	return (0);
}

/* int
 * res_queriesmatch(buf1, eom1, buf2, eom2)
 *	is there a 1:1 mapping of (name,type,class)
 *	in (buf1,eom1) and (buf2,eom2)?
 * returns:
 *	-1 : format error
 *	0  : not a 1:1 mapping
 *	>0 : is a 1:1 mapping
 * author:
 *	paul vixie, 29may94
 */
int
res_queriesmatch(const u_char *buf1, const u_char *eom1,
		 const u_char *buf2, const u_char *eom2)
{
	const u_char *cp = buf1 + HFIXEDSZ;
	int qdcount = ntohs(((const HEADER *)buf1)->qdcount);

	if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
		return (-1);

	/*
	 * Only header section present in replies to
	 * dynamic update packets.
	 */
	if ( (((const HEADER *)buf1)->opcode == ns_o_update) &&
	     (((const HEADER *)buf2)->opcode == ns_o_update) )
		return (1);

	if (qdcount != ntohs(((const HEADER*)buf2)->qdcount))
		return (0);
	while (qdcount-- > 0) {
		char tname[MAXDNAME+1];
		int n, ttype, tclass;

		n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
		if (n < 0)
			return (-1);
		cp += n;
		if (cp + 2 * INT16SZ > eom1)
			return (-1);
		ttype = getUShort(cp);	cp += INT16SZ;
		tclass = getUShort(cp); cp += INT16SZ;
		if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
			return (0);
	}
	return (1);
}

isc_result_t
res_nsend(res_state statp,
	  double *buf, unsigned buflen,
	  double *ans, unsigned anssiz, unsigned *ansret)
{
	HEADER *hp = (HEADER *) buf;
	HEADER *anhp = (HEADER *) ans;
	int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns, n;
	u_int badns;	/* XXX NSMAX can't exceed #/bits in this variable */
	static int highestFD = FD_SETSIZE - 1;

	if (anssiz < HFIXEDSZ) {
		return ISC_R_INVALIDARG;
	}
	DprintQ((statp->options & RES_DEBUG) ||
		(statp->pfcode & RES_PRF_QUERY),
		(stdout, ";; res_send()\n"), buf, buflen);
	v_circuit = (statp->options & RES_USEVC) || buflen > PACKETSZ;
	gotsomewhere = 0;
	connreset = 0;
	terrno = ISC_R_TIMEDOUT;
	badns = 0;

	/*
	 * Some callers want to even out the load on their resolver list.
	 */
	if (statp->nscount > 0 && (statp->options & RES_ROTATE) != 0) {
		struct sockaddr_in ina;
		int lastns = statp->nscount - 1;

		ina = statp->nsaddr_list[0];
		for (ns = 0; ns < lastns; ns++)
			statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1];
		statp->nsaddr_list[lastns] = ina;
	}

#if defined (TRACING)
	trace_mr_statp_setup (statp);
#endif

	/*
	 * Send request, RETRY times, or until successful
	 */
	for (try = 0; try < statp->retry; try++) {
	    for (ns = 0; ns < statp->nscount; ns++) {
		struct sockaddr_in *nsap = &statp->nsaddr_list[ns];
 same_ns:
		if (badns & (1 << ns)) {
			res_nclose(statp);
			goto next_ns;
		}

		if (statp->qhook) {
			int done = 0, loops = 0;

			do {
				res_sendhookact act;

				act = (*statp->qhook)(&nsap, &buf, &buflen,
						      ans, anssiz, &resplen);
				switch (act) {
				case res_goahead:
					done = 1;
					break;
				case res_nextns:
					res_nclose(statp);
					goto next_ns;
				case res_done:
					return (resplen);
				case res_modified:
					/* give the hook another try */
					if (++loops < 42) /*doug adams*/
						break;
					/*FALLTHROUGH*/
				case res_error:
					/*FALLTHROUGH*/
				default:
					return ISC_R_UNEXPECTED;
				}
			} while (!done);
		}

		Dprint(statp->options & RES_DEBUG,
		       (stdout, ";; Querying server (# %d) address = %s\n",
			ns + 1, inet_ntoa(nsap->sin_addr)));

		if (v_circuit) {
			int truncated;
			struct iovec iov[2];
			u_short len;
			u_char *cp;

			/* Use VC; at most one attempt per server. */
			try = statp->retry;
			truncated = 0;

			/* Are we still talking to whom we want to talk to? */
			if (statp->_sock >= 0 &&
			    (statp->_flags & RES_F_VC) != 0) {
				struct sockaddr_in peer;
				SOCKLEN_T size = sizeof(peer);

				if (getpeername(statp->_sock,
						(struct sockaddr *)&peer,
						&size) < 0) {
					res_nclose(statp);
					statp->_flags &= ~RES_F_VC;
				} else if (!cmpsock(&peer, nsap)) {
					res_nclose(statp);
					statp->_flags &= ~RES_F_VC;
				}
			}

			if (statp->_sock < 0 ||
			    (statp->_flags & RES_F_VC) == 0) {
				if (statp->_sock >= 0)
					res_nclose(statp);

				statp->_sock = socket(PF_INET,
						       SOCK_STREAM, 0);
				if (statp->_sock < 0 ||
				    statp->_sock > highestFD) {
					terrno = uerr2isc (errno);
					Perror(statp, stderr,
					       "socket(vc)", errno);
					return (-1);
				}
				errno = 0;
				if (connect(statp->_sock,
					    (struct sockaddr *)nsap,
					    sizeof *nsap) < 0) {
					terrno = uerr2isc (errno);
					Aerror(statp, stderr, "connect/vc",
					       errno, *nsap);
					badns |= (1 << ns);
					res_nclose(statp);
					goto next_ns;
				}
				statp->_flags |= RES_F_VC;
			}
			/*
			 * Send length & message
			 */
			putUShort((u_char*)&len, buflen);
			iov[0].iov_base = (caddr_t)&len;
			iov[0].iov_len = INT16SZ;
			iov[1].iov_base = (const caddr_t)buf;
			iov[1].iov_len = buflen;
			if (writev(statp->_sock, iov, 2) !=
			    (INT16SZ + buflen)) {
				terrno = uerr2isc (errno);
				Perror(statp, stderr, "write failed", errno);
				badns |= (1 << ns);
				res_nclose(statp);
				goto next_ns;
			}
			/*
			 * Receive length & response
			 */
 read_len:
			cp = (u_char *)ans;
			len = INT16SZ;
			while ((n = read(statp->_sock,
					 (char *)cp, (unsigned)len)) > 0) {
				cp += n;
				if ((len -= n) <= 0)
					break;
			}
			if (n <= 0) {
				terrno = uerr2isc (errno);
				Perror(statp, stderr, "read failed", errno);
				res_nclose(statp);
				/*
				 * A long running process might get its TCP
				 * connection reset if the remote server was
				 * restarted.  Requery the server instead of
				 * trying a new one.  When there is only one
				 * server, this means that a query might work
				 * instead of failing.  We only allow one reset
				 * per query to prevent looping.
				 */
				if (terrno == ISC_R_CONNREFUSED &&
				    !connreset) {
					connreset = 1;
					res_nclose(statp);
					goto same_ns;
				}
				res_nclose(statp);
				goto next_ns;
			}
			resplen = getUShort ((unsigned char *)ans);
			if (resplen > anssiz) {
				Dprint(statp->options & RES_DEBUG,
				       (stdout, ";; response truncated\n")
				       );
				truncated = 1;
				len = anssiz;
			} else
				len = resplen;
			if (len < HFIXEDSZ) {
				/*
				 * Undersized message.
				 */
				Dprint(statp->options & RES_DEBUG,